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The Heath H-89a supported two operating systems, HDOS and CP/M. Which of these two was the primary one? (P.S. It did not have an S-100 bus.)
– traalApr 30 '17 at 6:23

3

Definitely lots. And S-100 was one of the bus systems popular during CP/M times - But certainly not the only one.
– tofroApr 30 '17 at 7:56

1

@traal I take an operational definition of primary operating system: which was the more commonly used in practice? E.g. the IBM PC supported four operating systems quite early on, but there's no question that MSDOS was the primary. Of course it would be ideal to be able to get actual numeric breakdown of which was used how often.
– rwallaceApr 30 '17 at 11:41

1

Immediately adding hugely to the non-S-100 count: the Amstrad PCW. Per Wikipedia (so, ummmm, yeah) that's close to 8m CP/M machines immediately (the last model it refers to barely sold).
– TommyApr 30 '17 at 13:38

2

The count also depends on CP/M vs. CP/M family of operating systems - i.e., MP/M (multiuser), CP/M-86 (for 16-bit CPUs - this is what was available (but hardly sold any) for the IBM PC), MP/M-86 (16-bit and multiuser), Concurrent CPM (single user but multi-tasking - essentially MP/M with only one terminal), Concurrent DOS (multiuser with a moderate amount of MS-DOS compatibility), etc. All of those could be considered variants or descendants of CP/M, though I would leave off DR-DOS which was really a MS-DOS replacement and AFAIK does not have any CPM function call compatibility.
– manassehkatzMay 2 '17 at 22:22